The brazing of titanium and titanium alloys used in the construction of high speed aircraft may be accomplished with a brazing alloy consisting principally of aluminum. Such an alloy is described in U.S. Pat. No. 3,660,891 and comprises aluminum, copper and silicon. The copper serves to depress the alloy melting temperature but also decreases its fluidity. On the other hand, the silicon is believed to reduce the solvent action and to increase fluidity. The copper content is kept at a low level to minimize the formation of the brittle intermetallic phase of copper aluminide (CuAl.sub.2). The disadvantage of high levels of silicon in the alloy as proposed in the above patent is the tendency of this component to precipitate into crystals during the brazing process thereby impairing the strength of the resulting joint.
The alloy of this invention utilizes tin in addition to aluminum, copper and silicon to substantially improve the wetting capability. This increased wetting capability permits reduction in the silicon content which in turn reduces the metalloid content in the brazed joint and correspondingly improves its mechanical properties.
A preferred embodiment of the invention comprises, expressed in percentages by weight, 3.0 silicon, 4.0 tin, 16.5 copper and 76.5 aluminum. An acceptable composition range in percentage by weight is 2.0 to 6.0 silicon, 2.5 to 6.0 tin, 13.0 to 28.0 copper and the balance aluminum.